Mahmoud-Ghoneim Doaa, Cherel Yan, Lemaire Laurent, de Certaines Jacques D, Maniere Armelle
LRMBM-IFR 91, Université de Rennes I et Centre Eugène Marquis, CS 34317 35043 Rennes, France.
Magn Reson Imaging. 2006 Feb;24(2):167-71. doi: 10.1016/j.mri.2005.10.002. Epub 2005 Dec 27.
The goals of the current study were (i) to introduce texture analysis on magnetic resonance imaging (MRI-TA) as a noninvasive method of muscle investigation that can discriminate three muscle conditions in rats; these are normal, atrophy and regeneration; and (ii) to show consistency between MRI-TA results and histological results of muscle type 2 fibers' cross-sectional area.
Twenty-three adult female Wistar rats were randomized into (i) control (C), (ii) immobilized (I) and (iii) recovering (R) groups. For the last two groups, the right hind limb calf muscles were immobilized against the abdomen for 14 days; then, the hind limb was remobilized only for the R group for 40 days. At the end of each experimental period, MRI was performed using 7-T magnet Bruker Avance DRX 300 (Bruker, Wissembourg); T1-weighted MRI acquisition parameters were applied to show predominantly muscle fibers. Rats were sacrificed, and the gastrocnemius muscle (GM) was excised immediately after imaging. (A) Histology: GM type 2 fibers (fast twitch) were selectively stained using the adenosine triphosphatase (ATPase) technique. The mean cross-sectional areas were compared between the three groups. (B) Image analysis: regions of interest (ROIs) were selected on GM MR images where statistical methods of texture analysis were applied followed by linear discriminant analysis (LDA) and classification.
Histological analysis showed that the fibers' mean cross-sectional areas on GM transversal sections represented a significant statistical difference between I and C rats (ANOVA, P<.001) as well as between R and I rats (ANOVA, P<.01), but not between C and R rats. Similarly, MRI-TA on GM transversal images detected different texture for each group with the highest discrimination values (Fisher F coefficient) between the C and I groups, as well as between I and R groups. The lowest discrimination values were found between C and R groups. LDA showed three texture classes schematically separated.
Quantitative results of MRI-TA were statistically consistent with histology. MRI-TA can be considered as a potentially interesting, reproducible and nondestructive method for muscle examination during atrophy and regeneration.
本研究的目标是：（i）引入磁共振成像纹理分析（MRI-TA）作为一种肌肉检查的非侵入性方法，该方法能够区分大鼠的三种肌肉状态，即正常、萎缩和再生；（ii）展示MRI-TA结果与2型肌纤维横截面积的组织学结果之间的一致性。
将23只成年雌性Wistar大鼠随机分为（i）对照组（C）、（ii）固定组（I）和（iii）恢复组（R）。对于后两组，将右后肢小腿肌肉固定于腹部14天；然后，仅对R组的后肢进行40天的重新活动。在每个实验期结束时，使用7-T磁体布鲁克Avance DRX 300（布鲁克，维森堡）进行MRI检查；应用T1加权MRI采集参数以主要显示肌纤维。对大鼠实施安乐死，并在成像后立即切除腓肠肌（GM）。（A）组织学：使用三磷酸腺苷酶（ATPase）技术对GM的2型纤维（快肌纤维）进行选择性染色。比较三组之间的平均横截面积。（B）图像分析：在GM MR图像上选择感兴趣区域（ROI），应用纹理分析的统计方法，随后进行线性判别分析（LDA）和分类。
组织学分析表明，GM横断面上纤维的平均横截面积在I组和C组大鼠之间（方差分析，P<0.001）以及R组和I组大鼠之间（方差分析，P<0.01）存在显著统计学差异，但在C组和R组大鼠之间无差异。同样，GM横断图像上的MRI-TA检测到每组具有不同的纹理，C组和I组之间以及I组和R组之间的判别值（费舍尔F系数）最高。C组和R组之间的判别值最低。LDA显示三个纹理类别大致分开。
MRI-TA的定量结果在统计学上与组织学一致。MRI-TA可被视为一种在萎缩和再生过程中用于肌肉检查的潜在有趣、可重复且非破坏性的方法。
